Voltage regulator



I April 27, 1948. G. w. COOK 2,440,246

VOLTAGE REGULATOR Filed Feb. 15, 1943 uffm INVENTOR.

'GEORGE W. COOK BY yflflw HIS ATTORNEY Patented Apr. 27, 1948 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 7 Claims.

This invention is a series voltage regulator designed to maintain a constant output potential notwithstanding changes in effective load resistance, without any impedance in the positive side of the line.

Regulation is accomplished by means of a carefully controlled negative resistance; that is, a device which associates an increase in current with a decrease in voltage.

Most voltage regulators now in use are compensators. in output has first taken place.

In many applications, truly constant voltage is a necessity, and the compensating type of mg ulator, which produces what might be termed back-lash in the output voltage, causes serious difficulties.

One of the objects of the present invention is to produce a simple voltage regulator for negative potentials, the correcting action of which occurs substantially simultaneously with the objectionable change.

Another object of the invention is to provide a voltage regulator, the action of which depends upon the load current through the regulator.

Further objects will appear from a reading of the following specification and claims.

The single figure of the drawing is a schematic wiring diagram of the voltage regulator of my invention.

Referring to the drawing, ID and H indicate terminals which provide a constant input to the regulator, l being the positive terminal and II, the negative; and i0 and H are respectively the positive and negative output terminals. The present invention, it will be understood, corrects for changes in load resistance, but not for changes in input voltage.

Arranged across the supply lines are a vacuum triode i2 and voltage dividing resistors l3 and I4.

No adjustment occurs until a change In parallel with tube I2 is a second vacuum tube l5. It will be apparent from the following description that a single tube, a duplex-triode, may be substituted for the two tubes I 2 and IS with no change in the functioning of the circuit.

The problem in regulating by the herein described regulator comprises adjusting the direct current plate resistance of tube l5 when the effective load resistance changes.

A resistor I6 is arranged in the negative line U so that all load current will pass therethrough, and the value of this resistor is chosen so that the voltage drop across it will properly bias the grid of tube l2. This bias voltage controls the conductivity of the tube.

A battery I! or other source of potential provides a nominal bias for tube IS. The final voltage applied to the grid of tube l5 will, however, be detemiined by the plate potential of tub l2, and hence by the conductivity of this tube.

It will be seen, therefore, that with a fixed load, certain fixed biases are developed for tubes I2 and i5, and that a certain output voltage is determined thereby.

The negative output terminal Ii is connected to the shunt l2, l3, Id at a point the potential of which is the same as the normal potential of terminal I I. as at point l8, and in this connecting I line is inserted a variable resistor IS.

The regulator is adjusted for proper operation in the following manner. A voltmeter is connected across the load (not shown) for observing the output voltage. The load resistance is momentarily decreased, as by shunting the load with a resistance equal to the load resistance. If the voltmeter shows a voltage decrease, the incremental resistance of the regulator is positive, and the value of resistor is must be increased.

With successive adjustments of resistor 19, it will be found that a shunting ol' the load will produce an increase in the output voltage. The incremental resistance of the regulator can then be said to be negative.

Th transition point in the adjustment of resistor is can readily be found by trial. The resistor is left at this setting; and, at this point the incremental resistance of the regulator within its operating range can be considered to be zero.

In the claims, applicant intends the term fixing the incremental resistance of the regulator within its operating range at zero to mean so adjusting the regulator that a change in load current, within limits, will not produce any substantial change in voltage across the load. Adjustment of the resistor iii varies the gain of tube l2 by adjusting its plate load resistors i3, id.

The circuit then will adjust for changes in load conditions, maintaining a constant voltage across the load, within the operating range of the regulator, the regulation depending, it will be seen. not on output voltage changes, but on the load current passing through resistor IS.

The above description is in specific terms. Certain changes and modifications will readily occur to those skilled in the art, however; and

it should therefore be understood that I consider my invention to include everything within the spirit of the invention that falls properl within the scope of the appended claims.

The invention described herein may be manufactured and/or used by or for the Government of the United States of America without the payment of any royalty thereon or therefor.

I claim:

1. A voltage regulator adapted to operate be tween a source of constant potential and a load, including a positive input line, a negative input line, a shunt across said lines including an electron tube, resistance means in the negative input line for producing a voltage drop depending on the flow of current through said load and through said shunt, means dependent upon the voltage drop across said resistance means for biasing the electron tube to vary the .conductivity thereof, another electron tube in the nega-- tive input line between the resistance means and the load, means for varying the plate reanode, a shunt across the supply lines including the cathode-anode path of said space charge device, resistance means in the negative line for producing a voltage drop depending on the flow of current through said load and through said shunt, means responsive to the voltage drop across said resistance means for biasing said space charge device, an electron tube in the negative line between the resistance means and the load, means dependent upon the conductivity of the space charge device for biasing the electron tube thereby to determine the conductivity of said tube, a positive and a negative outp'ut'line, and resistance means connecting said negative output line to said shunt for bringing to zero the incremental resistance of said regulator within its operating range.

3. A voltage regulator for negative potentials adapted to be located between asource of constant potential and a load subject to variations. comprising a resistor in the negative side of the supply line, an electron tube having an anode, means depending on the voltage drop across the said resistor for biasing said electron tube to vary the conductivity thereof, a space charge device having an anode and a grid, means conv necting the anode of the electron tube to the grid of the space charge device for fixing the anode resistance of the space charge device according to the anode potential of the electron tube by fixing the grid bias of the space charge device, thereby to vary the conductivity of the space charge device inversely to the variation in the conductivity of the said electron tube, and means for fixing at zero the incremental impedance of the regulator within its operating range.

4. The method of fixing the incremental resistance of a voltage regulator at zero to maintain constant voltage across a variable load without introducing impedance in the positive supply line, said regulator comprising an electron tube in the negative supply line and in series with the load, means shunting the load and said series tube including an electron tube having a plate load resistor, means varying the conductivity of said shunt tube responsive to variations in the fiow of current through said load, and means varying the conductivity of said series tube responsive to variations in the conductivity of said shunt tube, comprising selecting a point along the plate load resistor of said shunt tube having a potential substantially equal to the plate potential of said series tube, connecting a resistor between the plate of said series tube and said selected point, and adjusting the resistorto a value such that a change in load resistance will produce no change in voltage across the load.

5. A voltage regulator for maintaining constant voltage across a variable load without introducing impedance in the positive supply line. said regulator comprising an electron tube in the negative supply line and in series with the load, means shunting the load and said series tube including an electron tube having a plate load resistor, means varying the conductivity of said shunt tube responsive to variations in the fiow of current through said load, means varying the conductivity of said series tube responsive to variations in the conductivity of said shunt tube, and means for fixing the incrementalresistance of the regulator within its operating range at zero including a resistor connected between the plate of said series tube and a point along the plate load resistor of said shunt tube.

6. A voltage regulator for maintaining constant voltage across a variable load without introducing impedance in the positive supply line, said regulator comprising an electron tube in the negative supply line and in series with the load, a shunt across the load and said series electron tube, said shunt including an electron tube having a plate load resistor, means for varying the conductivity of said shunt tube inversely with variations in the flow of current through said load including a resistor in the negative line, means for varying the conductivity of said series tube inversely with changes in the conductivity of said shunt tube, and means for fixing the incremental resistance of the regulator within its operating range at zero including a resistor connected between the plate of said series tube and a point along the plate load resistor of said shunt tube.

7. A voltage regulator for -maintaining constant voltage across a variable load without in troducing impedance in the positive supply line, said regulator comprising an electron tube in the negative supply line and in series with the load, means shunting the load and said series tube including an electron tube having a. plate load resistor, means varying the conductivity of said shunt tube including a resistor in the negative supply line and in series with the shunt tube, said resistor also being in series with the load, means varying the conductivity of said series tube responsive to variations in the conductivity of said shunt tube, and means for fixing the incremental resistance of the regulator within its operating range at zero including a variable resistor connected between the plate of said series tube and a point along the plate load resistor of said shunt tube, said point having a potential normally substantially equal to the plate potential of said series tube.

GEORGE W. COOK.

REFERENCES CITED UNITED STATES PATENTS Name Date Braden Aug. 6, 1940 Number 

